KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 2. 125 



cesses would ha ve been very like pinnules; at the same ti me they would have differed 

 fi^om true pinnules in their situation, which is not at the upper end of a sub-axillary 

 brachial hut in the very middle of a brachial, as well as in their disposition at the same 

 side of the arm-branch instead of on alternate sides. It is difficult to suppose that these 

 processes can have been evolved from arm-branches, as true pinnules have been; it cer- 

 tainly looks as though they had been developed as outgrowths from the body of the 

 brachial. Since then these processes do not appear to be homologous with pinnules pro- 

 per, it is better to term them »false pinnules» (see Addenda). 



Anal struetures: x is shaped as in Cyothocrinus, but widens above. By a some- 

 what concave suture it supports a rather large median plate; on the left of this median 

 plate is a smaller plate that rests partly on x, partly on 1. post R; there was probably 

 a similar plate un the right (tig. 196). 



The Ventral Sac appears to be composed of 8 longitudinal rows of plates, which 

 are all hexagonal and some of which are folded. Three of these rows arise from the 

 proximal median plate, and of these three the middle row is rather smaller than the two 

 outer ones; i. e. the plates, though of the same height, are not so wide. The plates of 

 the median row are quite plane and so are those portions of the outer rows that abut 

 on it; the outer angles, however, of the outer rows are sharply pressed down and are 

 transversely folded. Each small plate on either side of the proximal median plate gives 

 rise to a similar series of hexagonal plates, which have both their lateral edges trans- 

 versely folded, the folds meeting those of the outer median rows. The inner side of the 

 tube appears to be composed of three rows of similarlv folded plates, thus completing the 

 total of 8. The folding is very strongly marked, especially along the sides of the tube, 

 and the appearance of fissures is thereby produced, as described by Wachsmdth and 

 Springek. As a matter of fäet, liowever, the hexagonal shape of the plates is never 

 cntirely löst, and it is perfectly certain that no fissures occur either in or between the 

 plates (fig. 197). 



The Stem, so far as preserved, is composed of alternate-sized ossicles (fig. 198 a). 

 There is a small pentagonal canal, and 5 radial sutures, which are not very distinct on 

 the outside of the stem, but are clear in section (fig. 198 b). 



Notes on Angelins figures: 



Tab. IV, fig. 8. In each ray the number of primibrachs is incorrect; the left-hand 

 branch of r. post. arm does not exist in the specimen; the infrabasals are too high. 



Tab. IV, fig. 8 a. This is stated in the explanation of the plate to be the same 

 specimen. This is very probably correct; and as the point of view is the same for both 

 figures, a comparison of them is instruetive. The present figure is in many respects more 

 correct, but the stem is not well rendered. The accompanying view of the arm from 

 above does not show the sutures, and has therefore led to the idea that the specimen 

 possessed recumbent pinnules. 



Tab. IV, fig. 8 b represents the distal end of a ventral sac as seen from below. It 

 is not part of the preceding specimen, as stated in the explanation to the plate. 



